


Twin Thing

by HolyMangos



Category: Rise of the Teenage Mutant Ninja Turtles (Cartoon 2018), Teenage Mutant Ninja Turtles - All Media Types
Genre: Brotherly Bonding, Family Fluff, Gen, Turtle Tots (TMNT), leo and donnie are twins this is the hill i will die on, leo fortunately knows this, with donnie it’s gonna be a bit harder to accept
Language: English
Status: Completed
Published: 2018-12-19
Updated: 2018-12-19
Packaged: 2019-09-23 00:32:04
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 5,595
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17070098
Author URL: https://archiveofourown.org/users/HolyMangos/pseuds/HolyMangos
Summary: Donnie is not a twin. He’s only six years old, but he knows this.Leo knows otherwise.





	Twin Thing

They're six years old, and Donnie knows their birthdays are never like the ones on TV. There's normally never cake, and, despite all of Don's years of asking, never once has he received his own robot assistant. They don't get to do the same sort of thing humans do on their birthdays either. No theme park trips or parties with friends.

If anything, their own personal birthday celebrations are full of disappointment that no one else in Donnie's family will admit to. He's newly six, Mikey's only five, and Raph's only seven, but Donnie at least knows. Sprinkled in the middle of their family, he knows a lot more than he probably should.

He knows he is not Leo's twin. Leo and Splinter can try to _insist_ , Splinter's reasoning likely being as a way to dress the lair up in recycled birthday gear one less time, and Leo's being... well Donnie is still not so sure.

When Donnie opens his gift from his _younger_ brother, the one he shares this day with, he stares at it for a lot longer than he probably should.

"I made it," Leo explains proudly, with chip crumbs smeared all over his face. "Mikey helped."

"I did, I did!" Mikey shouts back. "Leo and I did a good job!"

Donnie stares at the ugly thing for a few more seconds. It's basically a weird arts and crafts project. It's a little figure with pretzel stick arms and a square face. Maybe supposed to be a robot. Donnie doesn't know (or care). What he _does_ know, however, is that it's just another reminder of how he and Leo could never be twins. Donnie has all this creative talent and untapped potential that's been there for as long as he can remember. Leo doesn't even try on most things.

In the background of his thoughts, he can hear Mikey making robot noises as he imitates what their toy is supposed to be.

"...Thaaanks?" Donnie says, because their father once told them to always be polite to each other even when someone's being ridiculous. It's the right thing to do, Donnie knows.

"You're welcome," Leo says, not at all acknowledging the questionable tone. "My turn now to open gifts!"

Mikey slips down from his seat beside Raph to be closer to Leo. He even claps when Splinter pulls out Leo's own set of presents. Leo declares then anyway, "I'm gonna open Donnie's first!"

Donnie doesn't really acknowledge that until a few minutes later, when Leo wraps him up in a hug and thanks him for the Leo 3000, a brand new race car toy Donnie made just for him. It's 'specially designed and everything, Splinter helped him find the parts.

"You're welcome," Donnie says, shrugging off his brother's excitable grip. "Don't break it."

"I never break anything, twinsy!"

On the contrary, Donnie can think of several things Leonardo _has_ broken. There was dad's TV once—and wow had he been in for it then. There was the time he ripped up Raph's stuffed bear, fell and broke his own arm even. There was the coffee mug incident, and so many times with Donnie's inventions. There have been so many things Leonardo has broken, but Donnie doesn't let his refusal to acknowledge that bug him this time.

No, what bugs him more is the 'twinsy' comment. They are not _twins_.

Donnie can't help himself. "We're not twins. We _can't_ be twins. I am older than you. Probably a lot older."

Leo stares at him. Splinter stares at him. Donnie shifts his vision to the side and sees Raph staring at him too. And then when he looks back at Leo and Splinter, so is Mikey.

"We're not," he repeats, like his world depends on it.

Leo swears on his life. "We _are_. You're just a few minutes older."

"That's... no. That's not how it..."

"Perhaps, we should focus on the gift opening. Purple, how about you come sit by me?"

Donnie grumbles under his breath, but he still obeys his father. Crawling over and plopping down on Splinter's lap, he's still visibly upset. That becomes even more apparent when he wraps his father's arms around his small body like they're seatbelt straps. Seatbelt straps he's only ever seen detached and from broken cars that find their way into junkyards. Donnie sighs.

Leo offers him a confused glance, but then Mikey convinces him to open the present he made and Leo obeys. Raph scoots closer to sit by the group, eyeing Donnie even more so when he starts hiding his face against Splinter's shoulder.

Donnie wishes they had birthdays like the humans on TV do.

 

 

 

"Were you there when we were hatched? Do you remember what we were like?" Donnie overhears his _younger_ brother asking later that day, just before bed. His first thought is that Leo's in there with Mikey, trying to help Splinter get the youngest sibling to sleep by discussing happy memories of their past. When he peers into the doorway, he sees Leo alone with their father.

Donnie wants to roll his eyes at the cheesy question, _wants to walk away,_ but something stops him. He stays there, eavesdropping on the brother that calls himself his twin and the father that's raised them for as long as he can remember.

"It is a long and complicated matter, Blue. But yes, I have many fond memories of when you were all even younger. You were smaller than you are now, and you were still _always_ moving."

Leo laughs at that, but it's short and obvious that he's still thinking something through.

Donnie had expected Leo to move on from the whole semi-argument of their birthday, he has such a short attention span after all. But when Donnie hears his brother's next question, he's surprisingly only a little bit baffled. "Yeah, I know. I know. But..." Leo seems to take in a deep, dramatic breath, and he speaks so sincerely. "I've been thinking about Donnie. He doesn't think we're twins."

Splinter shushes him, probably pats the young child's head and mumbles reassurances that Donnie cannot see or hear. Donnie stares up above, breathing in deeply. He sorta wants to go in there and talk to Leo and Splinter himself, _but he hasn't done anything wrong_. He doesn't have anything to say, he's never been good at things like this.

Leo and Donnie are not twins. If he goes in there and backs that statement up with evidence, Leo will just feel worse.

"None of you boys may be related biologically, but that does not make you any less brothers. Purple and you are twins if _you_ believe you are twins," Splinter tells Leo.

"But Donnie... I dunno. He gets annoyed by the twin thing, I think."

"Do _you_ think you two are twins?"

"Yeah! Of course we are. We've always been!"

"Then there you go. This dilemma of yours seems very simple to me."

It's not that simple. Not to Donnie. Maybe not even to Leo anymore.

But Leo sniffs and seems to wipe his eyes and then Donnie is pretty sure he nods his agreement. He hears Splinter move closer to the door, so Don runs away before he can be spotted.

He thinks about what they said though. For a longer time than he'd like to admit.

 

 

 

The electricity they sometimes have flickers on and off with the television. They're all huddled together in their home, eyes glued to cartoons. It's late, a lot later than they're normally allowed to stay up, but Donnie is pretty sure that the only reason they're awake is because Splinter can't get Mikey to sleep otherwise. The youngest brother has been the victim of nightmares for the past week or so.

Splinter's plan has clearly backfired. Donnie looks off in the pile of blankets and sees that their father has fallen asleep alongside Michelangelo. Maybe not a total loss, but still somewhat one.

Raph is battling the pull of sleep too, and looks about ready to collapse. Donnie, meanwhile, is more than happy to stay up all day and do whatever he wants with his time. He would really like to go hang out away from the lair for a while, maybe explore the sewers all by himself once everyone's asleep.

He's always been so closely shadowed by family worrying about his shell when he does that. He'd like to just do research and explore on his own for a bit. There's a lot he hasn't seen, so much adventure to be had with no fears or worries.

There's a weight against his side.

"Heeeey," Leo whisper-hisses suddenly. "Wanna play tag?"

No. No, he doesn't want to play tag. Donnie has never even liked tag all that much. He's trying to sit here, trying to think about what he wants to do when everyone falls asleep, and Leo, of all people, wants to play _tag_?

"I don't..." Don trails off, no clue what he means to say. "I don't want to play tag. Alright?"

"Oh. 'Kay."

Leo shuffles back into his spot, eyes focusing in on the television once again. Donnie blinks, but then nods. Because good. Leo _shouldn't_ push playing tag. Donnie just said he didn't want to play.

"It's just... sometimes tag gets boring," He explains anyway.

"Okay."

"I don't _not_ like it."

"That's cool."

"Sometimes I want to do my own things, Leo."

"I gotchu."

For whatever reason, Donnie feels like Leo still doesn't get him, but he leaves it be and backs off. Leo is sitting there happily, right next to Donnie, and doesn't look the least bit ready to turn in for the day. Donnie keeps sitting there too, and he doesn't say anything until twenty minutes into the next show, after Raph has long passed out. "I wanted to... maybe, go look around in the tunnels." He says it more like a question than a statement, and Leo looks back with wide, shining eyes. "That's why I'm not going to play tag."

" _I wanna come!_ " Leo shouts, excitedly.

Donnie sends him a knowing look. "This isn't a game, this is science."

"You're really into science, huh? Doesn't seem like you're _ever_ gonna get bored of it." Leo voices. Because _apparently_ the simple notion that he loves the subject is new to his brother. Donnie has collected textbook after textbook, conducted research after research, and is constantly trying to see the world through a scientific lens. But leave it to Leonardo to still be surprised.

Leo leans fully against Don's side, smiling widely. " _I_ can do science," he brags.

"No you can't."

"Uh huh, I can."

Leo sticks out his tongue. Donnie crosses his arms and rolls his eyes.

"Science is my thing," he finally says, eyes darting back towards Leo. "It's not yours."

"I think it could be though! We're twins after all. Maybe I'll be good at science too!"

Donnie doesn't even know how to respond to that.

"You're not good at science," He settles on. "And we're not twins."

"Yeah, we are."

"No, we're not."

"We are!"

"We're not!"

"Yes!"

"No!"

" _We're twins!_ "

" _NO_ , we're—" Donnie freezes in the middle of what he was going to say, ultimately stopping himself from getting too worked up. He doesn't want to yell. If he yells, he'll wake everyone else and then he'll just be in trouble. " _..._ It doesn't matter. If you want to come, okay. But don't be bored."

"I'm not gonna be bored," Leo swears on his life.

Donnie rolls his eyes, but mumbles his consent. Leo has the shortest attention span out of everybody he's ever known. That's not a lot of people, but Leo has them all beat when it comes to having no patience. Donnie figures he'll be bored no matter what he demands.

Leo isn't.

They spend hours down there, exploring tunnels and finding possible secret hideouts. That's what Leo calls them at least, Donnie is too busy creating a map of the sewer system to care. It's also kind of amusing that his brother thinks they can spend their lives in secret tunnels, like the club houses kids have on TV.

Donnie is truly baffled that Leo seems overjoyed to be beside him the whole trip. Even when Donnie starts spewing fun facts about the history of sewers, Leo is right there and he's listening. Don's been told on more than one occasion that those fun facts aren't actually all that fun. Not today though. Today Leo asks questions and takes an interest.

Donnie tells him everything he knows, from a sewer's purpose to what may be in the water, and Leo nods enthusiastically and actually contributes to the conversation to the best of his abilities. Donnie is left stunned for a lot of it, so when Leo decides they should hold a contest to see who can climb further into one tunnel, against all better judgement, he agrees.

Splinter finds them hours later, laughing and sitting at the edge by the water. They're both grounded just like that. Neither really mind. Donnie is much more focused on figuring out why Leo spent the majority of their secret trip asking questions and taking an interest. Leo laughs back that the whole thing was an adventure and he had fun, science and all.

And Leo, who's smiling and running freely and doesn't even care that Splinter is telling him to slow down, looks at Donnie. And Donnie looks back with the smallest hint of a smile.

 

 

 

"Purple," Splinter finds him one day, small hands on cords and disassembled electronics. "What are you doing?"

Donnie looks up, not at all shocked that his father is staring disapprovingly at the mess. "Fixing stuff," he answers easily.

"I was not aware that there was something that needed to be fixed?" Splinter asks. Donnie just shrugs and goes back to his work, practically ignoring the rat man's presence in every way.

After a few more minutes of this, Splinter heaves a sigh and points towards the space they've made into a hall. "Your brothers are playing hide and seek. Go. Entertain yourself with them."

"No, I'm good." Donnie retorts, tongue stuck out as he pushes two circuits together. His eyes grow wide when one heats up, and he quickly pulls them apart.

"It was not a question."

Donnie looks back up at his dad. He frowns. "I don't want to play hide and seek," he explains.

"Perhaps you can convince your brothers to play something else. What is that game you like? The one with the groups?"

"It's called Classifiers!" Donnie lights up immediately and pauses from his electronic study to discuss the game he's so proud of making. "I made it myself. You have to sort the different subjects into the best groups, but you have to do it all in your mind. Some even go in more than one! I based it off what I know helps brain development, and it also teaches importance lessons about classification."

"That sounds very interesting, I'm sure they'd love to play that."

Standing up now, Donnie has forgone what he was doing. But as he sends a distant glance to where his brothers are, he still knows he would rather be experimenting with the TV wires. "I don't think they would. And I don't want to play Classifiers right now anyway."

"I'm sure there is something you would all enjoying doing then. _Go_. See what is it while I fix whatever you did to my television."

Donnie stares back at the hallway, and then his gaze drifts to the mess he's made. Silent for a couple moments, it takes awhile to decline again. He tells Splinter, even more insistently, "no thanks. I'm good here."

" _Purple_."

"Yes?" Donnie asks bashfully. Wide eyes fluttering as a show of innocence.

" _Your brothers_."

"Are good playing over there! I'm good here!" Donnie promises, motioning wildly at the hall. And then he goes to back to adjusting the wires and circuits and disassembled electronics like the conversation never happened, and Splinter debates whether or not to surrender right then and there.

Instead, he picks up the small child. Donnie squirms around in his grasp, barking out complaints similar to _put me down_ and _I don't want to play,_ followed by the ever favorite _I was doing something important._

Splinter does not respond. He just holds Donatello close to his chest and starts walking. The six year old kicks him in the stomach and it takes a lot more to hold his own than Splinter would like to admit. Donnie thrashes around, demanding to be returned to the floor, but Splinter has no such wishes.

At some point, they're walking through the hallway. Leo, Raph and Mikey watch curiously as Splinter comes marching through with Donnie in his arms, and Donnie can't help but be confused when he's not placed down there with them.

That confusion only lasts for a few more seconds, because finally they enter the shared bedroom of the brothers, and Splinter plops him down on the cot.

"I was doing something important," Donnie repeats. Arms crossed and visible scowl on his face, he looks away.

"What were you doing?"

"...I wanted to see what was in the TV. And in everythin' else."

Splinter sighs. "We have discussed taking things apart without permission, haven't we?"

Donnie huffs, loud and angry, but he nods his head.

Splinter sighs again.

"Why did you want to see what is inside? Have you not already taken the tv apart? Have you not seen it all?" The rat man questions, clearly aggravated by what has happened to his beloved form of entertainment.

"I was bored," Don answers simply.

"You cannot disobey rules because you are _bored_. There is much for you to do. You could have played with your siblings, _like I continued to ask of you which would have avoided this conversation._ You could have colored, could have _watched_ TV _._ Boredom is no excuse."

Donnie does not really care.

He's not going to explain that he didn't—and still doesn't—want to play with Leo, Raph and Mikey. He spends everyday with them, personal space is a good thing sometimes. Personal space helps you think things through, he's learned. Personal space gives you time to research and experiment on things for yourself.

Coloring is no fun, not when there's no ideas in your brain that you want to draw. Nothing good was playing on TV either.

Splinter sighs for the millionth time in this conversation, Donnie feels.

Then, he tells him that he needs to go back and fix the TV. And if they ever have another incident like this, Splinter will no longer be so understanding and there will be a grounding. Donnie doesn't want another week of just sitting around without textbooks or his other favorite things _,_ so he agrees.

He walks back through the hall, past his brothers who are watching him again. Leo waves. Mikey asks what he did. Raph says _it was the TV wasn't it._ And Donnie does not answer.

 

 

 

Water rushes in a quick steady stream, drenching the furniture and all their belongings. Their bedroom is already nearly destroyed, tampered with by the rising sewer water. Donnie's piles of inventions have all short circuited and, as a mere six year old genius, that basically means everything.

"I don't wanna _leave_ ," Donnie begs, sprawled out on the floor of their living room—what is soon to no longer be a room livable enough for four young mutant turtles and one old mutant rat. No longer will it be their lair, no longer will it be home, and Donnie starts crying even harder when he thinks that horrible thought. "We don't need to move!"

They do. They do need to move. They need to get as faraway as they can with what they can carry as fast as possible.

"Would you rather die? That is what's gonna happen if you do not get a move on!" Splinter admonishes. His words do nothing but set Mikey off, and Mikey starts sobbing into Splinter's chest.

Donnie sits up, wiping his face and trying to control his tears. "My... my... even my calculator is broken, I checked." He explains, like that warrants all this. He starts crying again, and Splinter heaves a gigantic sigh.

Raph rushes into the room, carrying plastic bags filled to the brim with everything salvable he can find. He's shaking all over, but he stomps through the water towards their father. He doesn't even complain when Splinter hands him Mikey. It's one of the those things that comes with being the oldest and the biggest.

Leo follows suit. He holds his pile in his backpack as he moves out of the room. Splashing the water out of the way, he slides toward their group. Donnie's sitting all the way up now, he wants to try to be as calm as everyone else.

He sees the tears on Leo's face and does not feel calm at all.

"Do you have _everything you need?"_ Splinter asks one final time. It's clear he's expecting the answer to be yes, but he turns to Donnie and looks at him sharply. "Donatello. I am not kidding! If you want to keep anything, go get it _now_."

"Donnie, come on." Raph tries to help him to his feet, but Donnie shoves him away. "You should want to keep _something_."

"I can.. I can make a draining system. I can make a draining system and then we don't have to—"

"—Donnie." Leo begs, and the tears start streaming down his face. "We.. we gotta _go_."

Raph holds Mikey up a little higher, because when Leo says they have to leave Mikey starts begging to stay. He can't bring his favorite stuffed animal with him. That poor guy has been swallowed by the water and will likely never be seen again. Mikey doesn't get any of this like his older brothers do. He just wants to stay..

Donnie wants to be older. He _is_ older than Mikey. And he's pretty positive he's older than Leo. And part of being older is being as responsible as Splinter and Raph, and normally he tries. He tries so hard. He just wants to be _older_. Leo just wants them to be twins and he wants to be older. For so long he's insisted he is, but he's probably not acting like it right now.

Donnie wipes his face and stands up amid Mikey's sobs.

"I'm gonna be quick," he tells them. Splinter shoots him a serious look, but then Donnie races off to the room he's spent years sharing with his brothers and unzips his backpack, hoping to stuff in whatever he can find.

There's not much, and Donnie's about ready to start crying again.

But then Leo leans into the doorway, with feet that make ripples in the rising water. Don looks at him briefly, but he doesn't have time for games today. Splinter told him to hurry, he's gotta collect himself, he's gotta find what he can.

"Most of your stuff is in my bag, don't worry," Leo declares all of a sudden, and Donnie's full attention immediately goes back to his brother.

"What?"

Leo has his own stuff to pack. Leo has always had _too much stuff._ He keeps and treasures cereal boxes, wooden spoons, cracked mugs, perfume bottles, whatever he can get his tiny hands on. Leo has more stuff than all of them combined, and if what Donnie heard was true, well then...

"Yeah. So just- just hurry, 'kay? We gotta go."

Donnie feels the tears rushing to his eyes.

He wraps his arms around his brother in a tight hug. Leo hugs back, hand on Donnie's bare shell. His small frame shakes even when he leans into the surprise embrace. Donnie's not sure whether Leo is scared, stressed or just overcome with emotion. Probably all three if he's being honest.

"You're a good brother," Donnie whispers through tears, head resting on Leonardo's shoulder.

Leo fails at not crying then, but Donnie doesn't say anything to that because he had his moment of full on sobbing just a little earlier. Leo quietly mumbles, "Y'know I want to stay too."

"We gotta go though," Donnie responds, copying what Leo had just said. Blinking tears out of his eyes, he tries to control himself. Going is the right thing if they want to live long lives. Here, they may be able to survive a couple hours, but after that? That would be it. Their father would be lucky to last minutes if the water rose even a little bit higher.

"Yeah," Leo sniffs.

Donnie lets go and Leo urges him towards the door. Still combating his own tears, Leo asks, "...Ready?"

"Yeah," Donnie replies. And then— "wait, no."

He rushes back to their dusted, worn down dresser and yanks it open. Digging around through the darkened area, Donnie pulls something out.

Leo's eyes grow big as he sees the same birthday gift he gave Donnie a few months ago.

"You kept it!" He shouts, jumping up and down. Water splashes in Don's direction, and he lifts a hand up to defend himself. "You kept my gift for you!"

Donnie grins back, but that only lasts a couple seconds because Splinter starts calling for them. Leo smiles the whole time as they dash back to their father and brothers.

 

 

 

Miles and miles they walk, and Donnie helps carry Leo's backpack for him. Leo and Mikey take turns riding on Splinter and Raph, and the week of trekking onwards becomes a distant blur when they finally find a safe enough place to stay.

 

 

 

They find a new home, a sanctuary, far away from loose pipes and dangerous levels of water.

"This will last us for many more years, I believe," Splinter told them when they first arrived. Nobody realty said anything to that, not right away.

"What if," Donnie had started to ask only several minutes later, tugging tightly onto his father's robe. "What if everything from the old lair washes above ground and the humans see it and—"

"—that will not happen," Splinter had assured. "It will spread out and travel deeper through the sewers. It will be fine."

Donnie nodded, but he didn't really believe that. He still doesn't now, as he sits against the wall and colors. Coloring is a good distraction. They were able to keep a whole pack of crayons and a couple sheets of clean paper. Coloring has always been something fun, and Donnie's just glad his beloved purple crayon made it through, even if he has no real ideas what to draw with it.

He looks up at their new home every few minutes. It's empty and ugly and way too cold. They couldn't bring more than a couple blankets, hopefully that'll be enough. Hopefully they'll find furniture, hopefully they'll fix this place, hopefully it'll look better after a week or so, _hopefully_ —

Many birthdays and holidays and celebrations, and life in general, will be spent here. Donnie's only six years old, _but he doesn't like change_. His entire life has been lived in their old home. He _liked_ their old home.

Leo slinks to his side, gaze darting around the new place. He slides away from the wall, plopping down on Donnie's left. He barley stops staring at the open space, even when he lands. He only occasionally glances at what Don's doing. Donnie doesn't really have the energy to pay it any mind.

He saw Splinter start trying to move things around, Raph is probably with him. Mikey is probably sleeping. They don't even have that much stuff, but apparently it's enough to make Splinter want to organize.

Donnie would have once thought Leo would go with them. That way he could make sure what's his stays his. Now he's not so sure.

"This place is big," Leo declares instead.

"Yeah," Donnie replies while scribbling. He's not coloring a real picture right now like he normally does. No untapped potential or creative talent being used. He just feels like scribbling lines on the paper. Maybe it's a waste of materials, he doesn't know, but he hasn't been yelled at yet, so who cares.

He cares. Kinda. His whole sense of self feels more than a bit off. But who would miss one piece of paper when almost all their belongings are gone anyway?

"Dad said we might be able to have our own rooms here! My room is going to be blue. Aqua, sky, literally every shade of blue your brain can think of!" Leo exclaims, proudly.

Donnie glances up, looks at the big, empty space of their new lair. Having their own rooms was never something he thought about, simply because it was never an option. He still doesn't know if he wants that. Their new lair is a lot roomier, sure, but the close knit quarters of home were comforting. If he woke up in the middle of the night, his brothers would be there. Splinter would be there. Now he has no idea where Splinter, Raph and Mikey even are in this place.

"You okay?" Leo asks, arm against Don's shoulder.

Donnie nods, mumbles back, " _I'm fine,_ " but then he slowly turns to face his brother so he can ask him the same question. "Are you okay?"

"Yeah! I think... I think I could get used to it here," Leo answers, honestly. "I already have a vision of what this place should look like! And Raph said Dad said we can decorate however we please."

Donnie looks away. "Oh."

"It's okay if you don't love it right now," Leo adds quickly. He sits up a little, but turns to face Donnie which, as a result, gets his brother to look at him again. "We basically just got here. I don't think Mikey likes it either."

"How did you know I don't..."

Leo taps his head knowingly. "It's a twin thing."

"...We're not- but _we're not_.." Donnie stutters and stumbles before he eventually settles on the ever classic, "...Okay."

He nods like he gets it, but there's still so much he _doesn't get_. That is not a proper explanation at all. He's never even heard of a _twin thing_. So after a couple more seconds of pondering this, he decides to ask the number one question on his mind. "What is a twin thing?"

"A twin thing is like," Leo leans back, with arms crossed behind his head as he looks up at the sewers. "We're brothers, you know? But also best friends. We get each other. We get things other people normally wouldn't."

"One time I was reading a study about twins. Human twins sometimes play together in the womb," Donnie offers suddenly. Then, feeling the need to furthermore explain, he clarifies, "...Not us though. Turtles come from eggs."

"Donnie. You read—"

"—I also read that most of the time one twin is born first. And then the other one comes. But they're still twins. I was hatched first, and then you were hatched. From separate mothers, you know. Most importantly, I'm still older, okay?"

Leo grabs him in a hug.

Donnie sits there, coloring abandoned as he pats his brother's shell. His little brother's shell. Who is also apparently his twin. Who is furthermore a different species. Their family has never been like the ones on TV, but still, Donnie thinks, they have their moments.

They hug for a long time, long enough for Splinter to come and try to get them ready for setting up. Their father walks into the room slowly, almost like he knows what's going on.

"I love your drawing, Purple. Very beautiful," he says so sincerely after Leo and Donnie part.

 

 

 

They're fourteen years old now. Officially and everything. Splinter, Raph, Mikey and April sing happy birthday—and there's a _cake_ , thanks to April and her wad of cash that Raph swears he'll find a way to pay back. April insists it's not, and never will be, a problem.

Donnie sits beside Leo, who's swaying back and forth with the music. Donnie rolls his eyes, but Leo grins, and slowly Donnie grins back.

Their birthdays are never like the ones on TV. They can't be. They're mutant turtles living underground in the sewers.

Buuuut sometimes they're still alright. Most times, honestly. Leo hoots and hollers at the mention of their names in the song, and Donnie shakes his head in faux exasperation. And things are okay. It's in these rare moments when Donnie feels fond of these fools he calls a family.

His brother isn't obsessed with science, nor does he care to think ahead. He gets too focused on random things sometimes. He'd much rather do something that's fun than something that's educational.

But Donnie has come to note over the years that _Leo tries_. He tries with a lot more things than Donnie has ever given him credit for.

And maybe they're not biologically twin brothers, (they're not. they're definitely not, science proves that), but there are things that Donnie has learned to let go of in his life, and that's one of them. He still is the second eldest brother who they all depend on for his brains, that'll probably never change, but it doesn't make him any less of Leo's twin.

"Happy birthday, twinsy," Leo whispers when the song comes to a close, and they're ready to blow out the candles.

Donnie smirks, rolls his eyes, and then nudges Leo's side. "Happy birthday twin."

They blow out the candles.

**Author's Note:**

> i love how basically the whole fandom has agreed that donnie and leo are twins (as we all should). i had to write something for that


End file.
